cpu: Split the traffic generator into two classes

The traffic generator currently assumes that it is always driven from
a configuration file. Split it into a base class (BaseTrafficGen) that
handles basic packet generation and a derived class that implements
the config handling (TrafficGen).

Change-Id: I9407f04c40ad7e40a263c8d1ef29d37ff8e6f1b4
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/11515

cpu-tester: Added ExitGen to TrafficGen

Added the ExitGen to the TrafficGenerator which allows an EXIT
state to be added to the TrafficGen configuration file. Entering this
state will cause the simulation to exit immediately. Please note that
if multiple TrafficGen instances have an EXIT state, the first of these
to be encountered will cause the simulation to terminate.

Change-Id: Ieea51f05ffb780771f007787a2b119f79143d0c1
Reviewed-by: Sascha Bischoff <sascha.bischoff@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5723
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>

cpu-tester: Refactoring traffic generators into separate files.

Change-Id: I2372a0a88e276dcb0c06c3d0a789e010cfba8013
Reviewed-by: Matteo Andreozzi <matteo.andreozzi@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/5722
Maintainer: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>

cpu, gpu-compute: Replace EventWrapper use with EventFunctionWrapper

Change-Id: Idd5992463bcf9154f823b82461070d1f1842cea3
Signed-off-by: Sean Wilson <spwilson2@wisc.edu>
Reviewed-on: https://gem5-review.googlesource.com/3746
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Reviewed-by: Jason Lowe-Power <jason@lowepower.com>
Maintainer: Jason Lowe-Power <jason@lowepower.com>

mem: Resolve TrafficGen trace relative to the config

The traffic generator currently resolves relative trace paths relative
to gem5's current working directory. This can lead to surprising
results for relative paths where the expectation would normally be
that they are resolved relative to the configuration file. This
changeset implements config-relative trace file lookups. The old
behavior is kept as a fallback for configs that expect that behavior.

Change-Id: I1bda4e16725842666ffc37dcb6838c23a6ff138c
Signed-off-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Curtis Dunham <curtis.dunham@arm.com>

cpu: Add a basic progress check to the TrafficGen

This patch adds a progress check to the TrafficGen so that it is
easier to detect deadlock scenarios where the generator gets stuck
waiting for a retry, and makes no further progress.

Change-Id: Ifb8779ad0939f52c0518d0e867bac73f99b82e2b
Reviewed-by: Andreas Sandberg <andreas.sandberg@arm.com>
Reviewed-by: Radhika Jagtap <radhika.jagtap@arm.com>

cpu: warn if TrafficGen is suppressing a large numer of packets

Add a basic warning for every 10000 packet that is suppressed to alert
the user.

misc: Add explicit overrides and fix other clang >= 3.5 issues

This patch adds explicit overrides as this is now required when using
"-Wall" with clang >= 3.5, the latter now part of the most recent
XCode. The patch consequently removes "virtual" for those methods
where "override" is added. The latter should be enough of an
indication.

As part of this patch, a few minor issues that clang >= 3.5 complains
about are also resolved (unused methods and variables).

misc: Remove redundant compiler-specific defines

This patch moves away from using M5_ATTR_OVERRIDE and the m5::hashmap
(and similar) abstractions, as these are no longer needed with gcc 4.7
and clang 3.1 as minimum compiler versions.

sim: Refactor and simplify the drain API

The drain() call currently passes around a DrainManager pointer, which
is now completely pointless since there is only ever one global
DrainManager in the system. It also contains vestiges from the time
when SimObjects had to keep track of their child objects that needed
draining.

This changeset moves all of the DrainState handling to the Drainable
base class and changes the drain() and drainResume() calls to reflect
this. Particularly, the drain() call has been updated to take no
parameters (the DrainManager argument isn't needed) and return a
DrainState instead of an unsigned integer (there is no point returning
anything other than 0 or 1 any more). Drainable objects should return
either DrainState::Draining (equivalent to returning 1 in the old
system) if they need more time to drain or DrainState::Drained
(equivalent to returning 0 in the old system) if they are already in a
consistent state. Returning DrainState::Running is considered an
error.

Drain done signalling is now done through the signalDrainDone() method
in the Drainable class instead of using the DrainManager directly. The
new call checks if the state of the object is DrainState::Draining
before notifying the drain manager. This means that it is safe to call
signalDrainDone() without first checking if the simulator has
requested draining. The intention here is to reduce the code needed to
implement draining in simple objects.

sim: Refactor the serialization base class

Objects that are can be serialized are supposed to inherit from the
Serializable class. This class is meant to provide a unified API for
such objects. However, so far it has mainly been used by SimObjects
due to some fundamental design limitations. This changeset redesigns
to the serialization interface to make it more generic and hide the
underlying checkpoint storage. Specifically:

* Add a set of APIs to serialize into a subsection of the current
object. Previously, objects that needed this functionality would
use ad-hoc solutions using nameOut() and section name
generation. In the new world, an object that implements the
interface has the methods serializeSection() and
unserializeSection() that serialize into a named /subsection/ of
the current object. Calling serialize() serializes an object into
the current section.

* Move the name() method from Serializable to SimObject as it is no
longer needed for serialization. The fully qualified section name
is generated by the main serialization code on the fly as objects
serialize sub-objects.

* Add a scoped ScopedCheckpointSection helper class. Some objects
need to serialize data structures, that are not deriving from
Serializable, into subsections. Previously, this was done using
nameOut() and manual section name generation. To simplify this,
this changeset introduces a ScopedCheckpointSection() helper
class. When this class is instantiated, it adds a new /subsection/
and subsequent serialization calls during the lifetime of this
helper class happen inside this section (or a subsection in case
of nested sections).

* The serialize() call is now const which prevents accidental state
manipulation during serialization. Objects that rely on modifying
state can use the serializeOld() call instead. The default
implementation simply calls serialize(). Note: The old-style calls
need to be explicitly called using the
serializeOld()/serializeSectionOld() style APIs. These are used by
default when serializing SimObjects.

* Both the input and output checkpoints now use their own named
types. This hides underlying checkpoint implementation from
objects that need checkpointing and makes it easier to change the
underlying checkpoint storage code.

mem: Split port retry for all different packet classes

This patch fixes a long-standing isue with the port flow
control. Before this patch the retry mechanism was shared between all
different packet classes. As a result, a snoop response could get
stuck behind a request waiting for a retry, even if the send/recv
functions were split. This caused message-dependent deadlocks in
stress-test scenarios.

The patch splits the retry into one per packet (message) class. Thus,
sendTimingReq has a corresponding recvReqRetry, sendTimingResp has
recvRespRetry etc. Most of the changes to the code involve simply
clarifying what type of request a specific object was accepting.

The biggest change in functionality is in the cache downstream packet
queue, facing the memory. This queue was shared by requests and snoop
responses, and it is now split into two queues, each with their own
flow control, but the same physical MasterPort. These changes fixes
the previously seen deadlocks.

cpu: TrafficGen sinks snoops without complaining

To be able to use the TrafficGen in a system with caches we need to
allow it to sink incoming snoop requests. By default the master port
panics, so silently ignore any snoops.

cpu: Add request elasticity to the traffic generator

This patch adds an optional request elasticity to the traffic
generator, effectievly compensating for it in the case of the linear
and random generators, and adding it in the case of the trace
generator. The accounting is left with the top-level traffic
generator, and the individual generators do the necessary math as part
of determining the next packet tick.

Note that in the linear and random generators we have to compensate
for the blocked time to not be elastic, i.e. without this patch the
aforementioned generators will slow down in the case of back-pressure.

cpu: Block traffic generator when requests have to retry

This patch changes the queued port for a conventional master port and
stalls the traffic generator when requests are not immediately
accepted. This is a first step to allowing elasticity in the injection
of requests.

The patch also adds stats for the sent packets and retries, and
slightly changes how the nextPacketTick and getNextPacket
interact. The advancing of the trace is now moved to getNextPacket and
nextPacketTick is only responsible for answering the question when the
next packet should be sent.

cpu: Move traffic generator sending out of generator states

This patch moves the responsibility for sending packets out of the
generator states and leaves it with the top-level traffic
generator. The main aim of this patch is to enable a transition to
non-queued ports, i.e. with send/retry flow control, and to do so it
is much more convenient to not wrap the port interactions and instead
leave it all local to the traffic generator.

The generator states now only govern when they are ready to send
something new, and the generation of the packets to send. They thus
have no knowledge of the port that is used.

cpu: Fold together the StateGraph and the TrafficGen

This patch simplifies the object hierarchy of the traffic generator by
getting rid of the StateGraph class and folding this functionality
into the traffic generator itself.

The main goal of this patch is to facilitate upcoming changes by
reducing the number of affected layers.

cpu: Make the generators usable outside the TrafficGen module

This patch enables the use of the generator behaviours outside the
TrafficGen module. This is useful e.g. to allow packet replay modes
for other devices in the system without having to replace them with a
TrafficGen in the configuration files.

This change also enables more specific behaviours to be composed as
specific modules, e.g. BaseBandModem can use a number of generators
and have application-specific parameters based around a specific set
of generators.

scons: Fix warnings issued by clang 3.2svn (XCode 4.6)

This patch fixes the warnings that clang3.2svn emit due to the "-Wall"
flag. There is one case of an uninitialised value in the ARM neon ISA
description, and then a whole range of unused private fields that are
pruned.

cpu: Share the send functionality between traffic generators

This patch moves the packet creating and sending to a member function
in the shared base class to avoid code duplication.

cpu: Add support for protobuf input for the trace generator

This patch adds support for reading input traces encoded using
protobuf according to what is done in the CommMonitor.

A follow-up patch adds a Python script that can be used to convert the
previously used ASCII traces to protobuf equivalents. The appropriate
regression input is updated as part of this patch.

cpu: Encapsulate traffic generator input in a stream

This patch encapsulates the traffic generator input in a stream class
such that the parsing is not visible to the trace generator. The
change takes us one step closer to using protobuf-based input traces
for the trace replay.

The functionality of the current input stream is identical to what it
was, and the ASCII format remains the same for now.

sim: Move the draining interface into a separate base class

This patch moves the draining interface from SimObject to a separate
class that can be used by any object needing draining. However,
objects not visible to the Python code (i.e., objects not deriving
from SimObject) still depend on their parents informing them when to
drain. This patch also gets rid of the CountedDrainEvent (which isn't
really an event) and replaces it with a DrainManager.

Port: Add protocol-agnostic ports in the port hierarchy

This patch adds an additional level of ports in the inheritance
hierarchy, separating out the protocol-specific and protocl-agnostic
parts. All the functionality related to the binding of ports is now
confined to use BaseMaster/BaseSlavePorts, and all the
protocol-specific parts stay in the Master/SlavePort. In the future it
will be possible to add other protocol-specific implementations.

The functions used in the binding of ports, i.e. getMaster/SlavePort
now use the base classes, and the index parameter is updated to use
the PortID typedef with the symbolic InvalidPortID as the default.

TrafficGen: Add a basic traffic generator

This patch adds a traffic generator to the code base. The generator is
aimed to be used as a black box model to create appropriate use-cases
and benchmarks for the memory system, and in particular the
interconnect and the memory controller.

The traffic generator is a master module, where the actual behaviour
is captured in a state-transition graph where each state generates
some sort of traffic. By constructing a graph it is possible to create
very elaborate scenarios from basic generators. Currencly the set of
generators include idling, linear address sweeps, random address
sequences and playback of traces (recording will be done by the
Communication Monitor in a follow-up patch). At the moment the graph
and the states are described in an ad-hoc line-based format, and in
the future this should be aligned with our used of e.g. the Google
protobufs. Similarly for the traces, the format is currently a
simplistic ad-hoc line-based format that merely serves as a starting
point.

In addition to being used as a black-box model for system components,
the traffic generator is also useful for creating test cases and
regressions for the interconnect and memory system. In future patches
we will use the traffic generator to create DRAM test cases for the
controller model.

The patch following this one adds a basic regressions which also
contains an example configuration script and trace file for playback.